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The way citizens perceive air quality has a huge impact on the public's willingness to contribute agendas that promote a sustainable future. Consequently, the scientific community wonders do the sudden and short-term shifts in air quality (such as one caused by the COVID-19 pandemic) have the potential to induce long-term changes in community behavior. This study is based on the interpretation and analysis of a facultative survey administered to the student population of a medium-sized university city in the Balkans. The study's goal is to identify the types and strengths of factors that influence students' perceptions of air quality. In this regard, six classification algorithms were compared in order to select the one with the best fit between students' demographics, traveling habits, and air quality perception. Individual variable influence revealed that Weekly lectures attendance and Distances students travel determine the perception of air quality more than Gender and Permanent place of residence. According to the study, potential commuting reorganization should target those living 2-4 km from the faculty building. Students who regularly attend lectures are likely to be willing to rely on better-organized public transport. Those who do not, will generally contribute the initiative once the positive effects are evident.

Educational buildings have a significant share in the total number of buildings of public sector. Also, significant part of energy consumption belongs to these buildings. There are 15 kindergartens that are under 2 preschool institutions. Their specific annual heat consumptions are from 79.42 kWh/m2 to 491.52 kWh/m2 (from 106.02 kWh/m2 to 325 kWh/m2 for objects connected to the district heating system). The average specific annual heat consumption is about 22% more than the consumption in neighboring countries. Most kindergarten buildings were built in the '70 and '80s of the last century and do not have adequate thermal insulation. Based on the defined methodology, specific annual heat consumption of these buildings has been analyzed, priorities for reconstruction have been defined and measures for improvement of energy efficiency have been proposed. Conducted case study of implementing the proposed measures at 'Ciciban' kindergarten showed that savings could be from 36% to 58% in heat consumption.

To provide a warm place for the most vulnerable citizens during the 2022/2023 energy crisis, some municipalities have set up public halls as warming shelters. Thus, the present study analyzes the energy performance of a gymnasium in Southeastern Europe that is repurposed to be used as public warming hall. The study conducted 15 EnergyPlus simulations, covering five states of gymnasium occupancy and three heating, ventilation and air conditioning scenarios. Two scenarios were designed to reduce the possibility of viral disease transmission, in the case public health emergency occurs. The study indicates that gymnasiums with natural ventilation consume more energy than they would with more advanced HVAC systems. This way, when occupancy increases, building energy consumption decreases (from 171-102 kWh per m²). Contrary to that, in more advanced heating, ventilation and air conditioning scenarios, energy consumption slowly increases with the increase of occupancy. Due to the utilization of heat recovery and air re-circulation systems, these scenarios require approximately 60-80% less energy compared to the base scenario. The complex simulations performed in this study provided relatively simple formulas that can be extrapolated to determine hall energy performance for any hall occupancy. These formulas can be used by non-experts and applied to similar buildings in other locations. [ABSTRACT FROM AUTHOR]

Preschool buildings are among the biggest water consumers in the public buildings sector, in which efficient management of water consumption could make considerable savings in city budgets. The aim of this study was twofold: 1) to assess prognostic performances of 21 parameters that influence the water consumption and 2) to assess performances of two different approaches (statistical and machine learning-based) with 6 various predictive models for the estimation of water consumption by using the observed parameters. The considered data set was collected from the total share of public preschool buildings in the city of Kragujevac, Serbia, over a three-year period. Top-performing statistical-based model was multiple linear regression, while the best machine learning method was random forest. Particularly, random forest gained the best overall performances while the multiple linear regression showed the same precision as the random forest when dealing with buildings that consume more than 200m3 /month. It is found that both methods provide satisfying estimates, leaving for potential users to choose between better performances (random forest) or usability (multiple linear regression). [ABSTRACT FROM AUTHOR]

Sustainable housing is a worldwide challenge, while the case of Serbia could be an example of how complex the circumstances can be and how difficult it is to see the path towards sustainability. This paper sets out to answer multiple challenges; can energy-efficient, low-impact housing enter the market and respond to the needs of its population, potentially contributing to a more affordable and futureproof housing reality in Serbia? And does this demand rather different measure than the ones conventionally explored in innovative housing approaches elsewhere? To answer these questions, the paper starts from the preview of circumstances, then the methodology is proposed and explained, after which the possible building materials and technical installations for pilot multi-apartment Passive House are selected, and in the end, results are given and conclusions are drawn. Since the building is intended for a housing co-operative, both the affordability of the proposed solution and the environmental footprint has been comprehended by the methodology proposed. In the end, by carefully balancing the benefits of individual measures – favouring those that are cost-effective and discouraging the implementation of measures that are not, a viable pilot project that could step into the market-oriented society is selected. [ABSTRACT FROM AUTHOR]

The food industry uses a considerable amount of energy and that amount has been constantly growing with further developments in the sector. The growth of the milk processing industries with the production of dairy products has followed the trends in the food industry in general. The authors made a systematization of the literature data on the most common energy efficiency opportunities (measures) in diaries. Authors also present a methodology for conducting an energy audit in dairies based on ISO 50002 which includes a multi-criteria analysis for ranking energy efficiency opportunities. The proposed methodology was applied to a case study dairy in central Serbia. Taking into account interactions between opportunities, implementation of the proposed energy saving opportunities can ensure 11-15% energy savings for electricity and 20-23% of heat energy annually. [ABSTRACT FROM AUTHOR]

The implications of global warming on energy uses for heating and cooling in buildings are analysed in the paper. The research methodology is based on monitoring data on average daily temperature variation during a certain period and expected future temperature variation of existing mean daily temperatures according to a certain climate model. Developed model also uses the current real energy consumption of public buildings at a location and envisaged variation of cooling and heating degree day influenced by global warming. Based on the model, authors examine the influence of global warming on primary energy consumption for heating and cooling in public buildings in a city of Kragujevac, Serbia. The results show that a consequence of global warming should be a significant reduction of total primary energy consumption for heating and cooling in the public buildings. Possible increase in mean annual temperature of 3.8 °C till the end of the century has an impact to the reduction of primary energy use for heating for 35.7% in public buildings in Kragujevac, while predicted consumption of primary energy for cooling will be almost five times higher than nowadays. [ABSTRACT FROM AUTHOR]

The use of renewable energy sources for electricity generation in the Western Balkan countries is analyzed in this review paper. Since those countries are part of EU or intend to be, data for Western Balkan are also compared with data for EU-28. The first part of the paper presents a brief overview of main promotion mechanism for electricity generation from renewable energy sources. As a dominant support policy, the feed-in tariff is more elaborated as an incentive measure and a detailed overview of the amount of tariffs and quotas for dominant technologies in the Western Balkan countries is presented. Furthermore, the current state of installed capacities and annual productions of three particular renewable electricity technologies (small hydro power, wind power, and solar photovoltaic) are analyzed in detailes. Based on presented data, there is a discussion and consideration of the impact of incentive measures on the electricity market and power production from renewable sources. [ABSTRACT FROM AUTHOR]

Wastewater from margarine production must be treated in a way and up to a level that will not pose a source of pollution before releasing into the recipient. The quality of effluent which can be discharged into the recipient is regulated by appropriate standards or regulations for every community. This paper presents the results of the application of a fat trap for wastewater treatment in a margarine production line in Serbia, in order to meet local regulations for wastewater quality and reduce pollution. Research was based on quarterly sampling performed during a period of 2.5 years. The wastewater after the treatment had a load with maximal measured concentration of TFM:39 mg/l, BOD5:100 mg/l, COD:115 mg/l and TSS:118 mg/l. The study demonstrated that a very simple technical solution such as a fat trap could give satisfactory results that are within the national standards. [ABSTRACT FROM PUBLISHER]

The objective of the paper is to show the implementation of infrared thermography within world class manufacturing maintenance strategy. The results from infrared thermography inspections in a food processing and packaging solutions company were presented. Applicability of the infrared thermography, during a two-year period, caused a substantial reduction of the potential breakdown in the pilot area. Upon feasibility confirmation, the proposed method was spread to other production equipment of the company. [ABSTRACT FROM AUTHOR]

Today, in Serbia there are several sites with installed combined heat and power facilities. The most of these plants, for various reasons, do not produce electricity. One such plant is "Energetika" (Kragujevac, Serbia), which is primarily a district heating company. Steam generator in the plant has been installed in the 1970's and has worked in one short period of time. Installed steam turbines are 8 MW and 20 MW rated power. "Energetika" in accordance with the general trend of increasing energy efficiency of production process initiated revitalization of the plant. This revitalization started with a study which approach and the results are briefly given in the paper. All results show that retrofit of facility should be acceptable for the management. Developed scenarios indicate that in the case of the limited resources optimal retrofit should start with smaller turbine (8 MW rated power) then after providing the funds should continue with the retrofit of 20 MW turbine. [ABSTRACT FROM AUTHOR]

Significant number of research projects in the area of renewable energy sources (especially for small hydro power plants) has been made within the Department for Energy and Process Engineering and Regional Euro Energy Efficiency Center at Faculty of Mechanical Engineering (University of Kragujevac, Serbia) since early eighties. The results are various; numerous domestic and international recognition and technical performance tell about the success of the research. Research projects have been following the technical and technological development of research equipment and economy growth. This has led to the development of software for designing turbines of small hydro power plants. In order to notify the public about possibilities of our software, in this paper is briefly described a mathematical model and procedures for calculating and designing of small hydro power for known conditions. As an argument for assessing the validity and potential of our research results is shown constructed small hydro power plant "Bosnia 1", 2 × 100 kW power. [ABSTRACT FROM AUTHOR]

This paper studies the influence of the magnetic field on the planar laminar steady flow of the ionized gas in the boundary layer. The present outer magnetic field is homogeneous and perpendicular to the body within the fluid. The gas of the same physical characteristics as the gas in the main flow is injected (ejected) through the contour of the body. The governing boundary layer equations for different forms of the electroconductivity variation law are transformed, brought to a generalized form and solved numerically in a four-parametric approx-imation. It has been determined that the magnetic field, through the magnetic parameter, has a great influence on certain quantities and characteristics of the boundary layer. It has also been shown that this parameter has an especially significant influence on the non-dimensional friction function, and hence the boundary layer separation point. [ABSTRACT FROM AUTHOR]

In this paper the relevant legislation for the geothermal energy in the European countries and Serbia is reviewed. There is a variety of the incentives for the geothermal production which are well known throughout the European Union. The governmental policies for the support of the geothermal development have so far focused on the power generation only. It is necessary to make serious efforts in order to harmonize the legislation and to simplify the procedures of establishing and implementing the policies for boosting the direct use of the geothermal energy. The Law on Energy of the Republic of Serbia which was adopted by the Parliament and the Energy Development Strategy of the Republic of Serbia until 2015 have defined the privileged power producers, but only by passing the Regulation on the incentive measures for the production of electricity using the renewable energy sources combined with the production of electricity and the thermal energy, which came into force on January 1st 2010. [ABSTRACT FROM AUTHOR]

This paper presents a methodology development and the results achieved in the process of establishing energy management system in the city of Kragujevac (Serbia) and in its public services. The paper is an overview of influential factors in the field of energy management, analyzing their impact on raising the energy efficiency of individual utility service and the city of Kragujevac, as a whole. The paper also presents the most interesting scientific and research projects realized in the co-operation of several actors which were co-ordinated by Regional Euro Energy Efficiency Center Kragujevac. The municipal companies together with the city administration are the direct beneficiaries of the results realized in the following areas: - Development of energy management in municipalities and the establishment of energy planning at the local level; - Improvement of municipal services by applying energy efficiency measures in public enterprises: "Energetika" (heating), "Cistoca" (communal waste management), and "Vodovod i kanalizacija" (water and waste water management). [ABSTRACT FROM AUTHOR]